Interpretive Summary: In legumes, seeds grow within pods, whose walls protect the developing seeds, as well as contribute nutrients to those seeds. The pathway for mineral flow from pod wall to seed involves the funiculus, a short segment of tissue, similar to an umbilical cord, which connects the pod wall to the seed's seed coat. To better understand how the dimensions of the funiculus might restrict or facilitate nutrient flow to developing seeds, we measured the length and width of the region where the funiculus attaches to the seed coat in developing chickpea seeds. Measurements taken throughout seed growth in five different cultivars demonstrated that the cross-sectional area of the funiculus changes over time. These results will be combined with mineral and dry weight data from developing seeds, to better understand the role of this critical structure in nutrient flow to seeds.

Technical Abstract:
Successful growth of seeds is dependent on the flow of nutrients from vegetative tissues to the developing ovule. In legumes like chickpea (Cicer arietinum L.), the pathway for this nutrient flow includes the pod wall surrounding the seeds, and ultimately the funiculus, which is the structure connecting the pod wall to the seed coat. The funiculus contains phloem and xylem vascular tissues, surrounded by parenchymatous cells; these tissues provide the pathway for delivering solutes to the developing seed. Because of the critical role that the funiculus plays in seed growth, we questioned whether the cross-sectional area of the funiculus might impose a restriction on the flow of nutrients. If funicular dimensions were rate-limiting to seed growth, then breeding for greater funicular cross-sectional area would be warranted to enhance chickpea productivity. Unfortunately, there are few data on the dimensions of the funiculus in chickpea, and these data are limited to dry, mature seeds. Thus, as a first step in understanding the growth dynamics of the chickpea funiculus, we characterized the width and length of the hilum (the oval-shaped region where the funiculus is attached to the seed coat) throughout the course of seed development.